The subject matter disclosed herein relates to multi-layer sensors used in eddy current probes and, in particular, to a sensor design having a linear drive conductor.
Eddy current probes are a form of nondestructive test devices that can be used to inspect test objects made of electrically conductive material to detect and analyze flaws in the test objects. Nondestructive testing allows an inspection technician to maneuver an eddy current probe over a surface of the test object during a test scan.
In an eddy current sensor, a magnetic field is used to induce an electrical current in the test object. The magnetic field is typically generated by one or more drive circuits typically in the form of electrically conductive drive coils, or windings, in the eddy current sensor. During operation of the probe, an electrical current travels through the drive coil, or coils, which generates a magnetic field that passes into the test object and induces an electrical current in the test object called an eddy current. The eddy current in the test object will itself generate a detectable magnetic field. This responsive magnetic field is then detected by a sense coil, or coils, and is analyzed by programmed electronics in the eddy current probe.
If the induced eddy current passes through a flaw or defect in the test object during the scan, the induced eddy current is perturbed and the sense coils will detect this as a varying impedance. In response to detecting the varying impedance, the sense coils will generate electrical signals that represent physical characteristics of the defect. By analyzing these electrical signals, various characteristics of the defect (e.g., location, size) can be determined. The impedance difference detected by the sense coils can be converted into a two-dimensional impedance data display.
Typical eddy current sensors utilize complementary, multi-turn coils in driving and sensing circuits which together form a relatively large footprint and are sensitive to noise effects caused by scanning edges of the test object.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.